1. Field of the Invention
This invention generally relates to beverage dispensers, more particularly, to insulated beverage dispensers.
2. Discussion of the Prior Art
It is known to provide commercial beverage dispensers with a double walled construction in which an outer, usually stainless steel housing surrounds and protects an inner liner, also made of steel, or made of glass. In the case of a glass liner, the liner has a mirrored surface to block passage of infrared radiation and conductive heat is blocked by foam insulation or other insulation between the outside of the liner and the inside of an outer housing that envelopes the glass liner. Likewise, if the liner is made of steel which is more robust than glass but which is also a good conductor of heat, it is necessary to provide solid foam insulation, such as cyanurethane or other like foam-type insulation. A problem with some dispensers using metal liners is that over time water may leak into the interior space between the outer housing and the inner liner and wet the solid foam insulation material. When this occurs the solid insulation material looses its insulating properties or these properties are overcome by the noninsulating, thermally conductive properties of the water.
While it is known in unrelated areas that vacuum is highly insulating, and so-called vacuum bottles are known, it has not been known to provide a commercial vacuum insulated beverage dispenser, due to the excessive pressures that are created that cause the component elements to distort, break or otherwise lose vacuum integrity when constructed of the usual thin wall materials needed for economy and weight reduction.
The inventor have therefore determined that there is a need for a vacuum insulated beverage dispenser design and method of making a vacuum insulated beverage dispenser that overcomes the shortcoming of known designs of insulated beverage dispensers.